This application claims the priority of 102 52 487.4 filed in Germany on Nov. 5, 2002, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an open-end spinning rotor, which—beginning at an open front side—comprises walls, one after the other, in the form of a lateral wall and in the form of a rotor base, comprising an inner contour bordering the lateral wall, which inner contour widens conically beginning from the open front side up to a fiber collecting groove, which has the largest inner diameter, also comprising an outer contour bordering the lateral wall, which outer contour increases in diameter from the open front side to its largest outer diameter size which is located in the area of the fiber collecting groove, also comprising the walls having different thicknesses, of which the wall thickness is at its thinnest in the area of the fiber collecting groove, while the wall thickness of the lateral wall is thinner than that of the rotor base.
An open-end spinning rotor of this type is prior art in German published patent application DE 199 10 277 (corresponding U.S. Pat. No. 6,195,976).
The known open-end spinning rotor is designed for speeds of up to 150,000 rpm, whereby the particular chosen dimensions should eliminate the risk of bursting due to too high a component tension. One of the ways this is achieved is that the open-end spinning rotor has its thinnest wall thickness in the area of its fiber collecting groove and that the wall thickness of the lateral wall is thinner than that of the rotor base. The wall thickness of the rotor base increases again in the direction of the shaft of the open-end spinning rotor. Thus an improved mass distribution and also a better running at high speeds is achieved. As the largest outer diameter is reduced despite maintaining the diameter of the fiber collecting groove, an additional reduction in weight is also achieved, which also contributes to the desired effect.
Despite these advantageous features, it was not recognized that in the case of the open-end spinning rotor, the maximum tension during operation is located in the middle of the lateral wall. It is, therefore, disadvantageous when the outer contour of the lateral wall in the known open-end spinning rotor is—in axial section—designed to be straight and that the wall thickness of the lateral wall increases constantly from the open front side to the fiber collecting groove.
It is an object of the present invention to further optimize the known open-end spinning rotor with regards to its operational component tension.
This object has been achieved in accordance with the present invention in that the outer contour of the lateral wall in axial section is at least partly convex in shape.
The wall thickness of the lateral wall, irrespective of whether viewed from the front side of the open-end spinning rotor or the largest outer diameter, first increases and then decreases again, according to the convex curve of the outer contour, to which—also in axial section—a straight-lined inner contour is disposed. The lateral wall thus has its greatest thickness in the area of its maximum tension. All the advantages which the open-end spinning rotor possessed in prior art are retained, in particular the thinnest wall thickness in the area of the fiber collecting groove, that is, where too much mass is undesirable in the case of high speeds.
In an embodiment of the present invention it is provided that the lateral wall comprises a curve in the convex designed area, which curve increases towards the open front side. For example, the curve—in axial section—in the area of the open front side can have a radius of 10 mm, while in a middle area of the lateral wall directly downstream thereof, the radius measures almost double the thickness. The wall thickness decreases more towards the open front side, that is, where less material is required as a result of the operational tensions.
It can be further provided that the lateral wall comprises a concavely designed transition area in the direction of the greatest diameter. The convexly designed area is located primarily in the middle area of the lateral wall and in the area of the open front side of the open-end spinning rotor and graduates via the concave form of the transitional area to the reduced wall thickness in the area of the fiber collecting groove.
These and further objects, features and advantages of the present invention will become more readily apparent from the following detailed description thereof when taken in conjunction with the drawing.